\title{Abstract Machine for Typed Feature Structures}
\author{Shuly Wintner \and Nissim Francez}
\date{Computer Science\\
        Technion, Israel Institute of Technology\\
        32000 Haifa, Israel\\ 
        {\tt \{shuly,francez\}@cs.technion.ac.il}}
\begin{abstract} 
This paper describes an abstract machine for linguistic formalisms
that are based on typed feature structures, such as HPSG.  The core
design of the abstract machine is given in detail, including the
compilation process from a high-level language to the abstract machine
language and the implementation of the abstract instructions.  The
machine's engine supports the unification of typed, possibly cyclic,
feature structures.  A separate module deals with control structures
and instructions to accommodate parsing for phrase structure grammars.
We treat the linguistic formalism as a high-level declarative
programming language, applying methods that were proved useful in
computer science to the study of natural languages: a grammar
specified using the formalism is endowed with an operational
semantics. \\
{\bf Topics:} Grammar formalisms, feature structures,
Parsing, Compilation, WAM.  \end{abstract}